package com.mislead.ikanxue.app.view;

import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.Scroller;
import com.mislead.ikanxue.app.R;
import java.util.LinkedList;
import java.util.List;

public class SwipeBackLayout extends FrameLayout {
  private static final String TAG = SwipeBackLayout.class.getSimpleName();
  private View mContentView;
  private int mTouchSlop;
  private int downX;
  private int downY;
  private int tempX;
  private Scroller mScroller;
  private int viewWidth;
  private boolean isSilding;
  private boolean isFinish;
  private Drawable mShadowDrawable;
  private Activity mActivity;
  private List<ViewPager> mViewPagers = new LinkedList<ViewPager>();

  public SwipeBackLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public SwipeBackLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    mScroller = new Scroller(context);

    mShadowDrawable = getResources().getDrawable(R.drawable.drawer_shadow);
  }

  public void attachToActivity(Activity activity) {
    mActivity = activity;
    TypedArray a =
        activity.getTheme().obtainStyledAttributes(new int[] { android.R.attr.windowBackground });
    int background = a.getResourceId(0, 0);
    a.recycle();

    ViewGroup decor = (ViewGroup) activity.getWindow().getDecorView();
    ViewGroup decorChild = (ViewGroup) decor.getChildAt(0);
    decorChild.setBackgroundResource(background);
    decor.removeView(decorChild);
    addView(decorChild);
    setContentView(decorChild);
    decor.addView(this);
  }

  private void setContentView(View decorChild) {
    mContentView = (View) decorChild.getParent();
  }

  /**
   * 处理viewpager滑动事件冲突
   */
  @Override public boolean onInterceptTouchEvent(MotionEvent ev) {
    ViewPager mViewPager = getTouchViewPager(mViewPagers, ev);
    Log.i(TAG, "mViewPager = " + mViewPager);

    if (mViewPager != null && mViewPager.getCurrentItem() != 0) {
      return super.onInterceptTouchEvent(ev);
    }

    switch (ev.getAction()) {
      case MotionEvent.ACTION_DOWN:
        downX = tempX = (int) ev.getRawX();
        downY = (int) ev.getRawY();
        break;
      case MotionEvent.ACTION_MOVE:
        int moveX = (int) ev.getRawX();
        if (moveX - downX > mTouchSlop && Math.abs((int) ev.getRawY() - downY) < mTouchSlop) {
          return true;
        }
        break;
    }

    return super.onInterceptTouchEvent(ev);
  }

  @Override public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
      case MotionEvent.ACTION_MOVE:
        int moveX = (int) event.getRawX();
        int deltaX = tempX - moveX;
        tempX = moveX;
        if (moveX - downX > mTouchSlop && Math.abs((int) event.getRawY() - downY) < mTouchSlop) {
          isSilding = true;
        }

        if (moveX - downX >= 0 && isSilding) {
          mContentView.scrollBy(deltaX, 0);
        }
        break;
      case MotionEvent.ACTION_UP:
        isSilding = false;
        if (mContentView.getScrollX() <= -viewWidth / 2) {
          isFinish = true;
          scrollRight();
        } else {
          scrollOrigin();
          isFinish = false;
        }
        break;
    }

    return true;
  }

  private void getAlLViewPager(List<ViewPager> mViewPagers, ViewGroup parent) {
    int childCount = parent.getChildCount();
    for (int i = 0; i < childCount; i++) {
      View child = parent.getChildAt(i);
      if (child instanceof ViewPager) {
        mViewPagers.add((ViewPager) child);
      } else if (child instanceof ViewGroup) {
        getAlLViewPager(mViewPagers, (ViewGroup) child);
      }
    }
  }

  private ViewPager getTouchViewPager(List<ViewPager> mViewPagers, MotionEvent ev) {
    if (mViewPagers == null || mViewPagers.size() == 0) {
      return null;
    }
    Rect mRect = new Rect();
    for (ViewPager v : mViewPagers) {
      v.getHitRect(mRect);

      if (mRect.contains((int) ev.getX(), (int) ev.getY())) {
        return v;
      }
    }
    return null;
  }

  @Override protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);
    if (changed) {
      viewWidth = this.getWidth();

      getAlLViewPager(mViewPagers, this);
      Log.i(TAG, "ViewPager size = " + mViewPagers.size());
    }
  }

  @Override protected void dispatchDraw(Canvas canvas) {
    super.dispatchDraw(canvas);
    if (mShadowDrawable != null && mContentView != null) {

      int left = mContentView.getLeft() - mShadowDrawable.getIntrinsicWidth();
      int right = left + mShadowDrawable.getIntrinsicWidth();
      int top = mContentView.getTop();
      int bottom = mContentView.getBottom();

      mShadowDrawable.setBounds(left, top, right, bottom);
      mShadowDrawable.draw(canvas);
    }
  }

  private void scrollRight() {
    final int delta = (viewWidth + mContentView.getScrollX());
    mScroller.startScroll(mContentView.getScrollX(), 0, -delta + 1, 0, Math.abs(delta));
    postInvalidate();
  }

  private void scrollOrigin() {
    int delta = mContentView.getScrollX();
    mScroller.startScroll(mContentView.getScrollX(), 0, -delta, 0, Math.abs(delta));
    postInvalidate();
  }

  @Override public void computeScroll() {
    if (mScroller.computeScrollOffset()) {
      mContentView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      postInvalidate();

      if (mScroller.isFinished() && isFinish) {
        mActivity.finish();
      }
    }
  }
}
